The invention relates generally to the field of homogenization systems in which a first liquid or solid component, such as water or finely divided calcium based sorbants, is homogenized with a second liquid component, such as fuel oil, and more particularly to such systems where the homogenization is accomplished using orifices to produce shearing and cavitation. Even more particularly, the invention relates to such systems in which the homogenization orifice is a component of a compensating valve which is automatically responsive to pressure conditions either downstream or upstream of the orifice. Still even more particularly, the invention relates to such systems which incorporate two compensating valve homogenization orifices, the first responsive to downstream pressure relative to the first valve and the second responsive to upstream pressure relative to the second valve.
It is known that effective intermixing of additional components such as fresh water into a fuel oil stream which is subsequently burned to operate combustion systems such as large boilers or diesel engines is advantageous with regard to reducing fuel consumption, corrosion, particulate emissions, soot, and other pollutants. It is also known that addition of other additives to the base fuel oil, typically designated as a No. 6 fuel oil, such as a lower sulfur content fuel oil or powdered limestone, also improve the performance. For ease of discussion in this specification, reference herein shall focus on the water and fuel oil mix, but it is to be understood that the apparatus involved would be suitable for many mixtures or blends. The technique known as cavitation or cavitating flow is known in the art, see for example U.S. Pat. No. 4,127,332, in which a stream of a liquid component, such as fuel oil, is passed through a relatively small orifice at high velocity, resulting in a cavitating free turbulent velocity shear layer, and a second component insoluble in the first component, such as water, is added at the orifice exit in order to intermix the two components into a homogenized mixture or colloidal suspension. The cavitating free turbulent velocity shear layer creates a flow regime where vapor bubbles form, expand, contract and ultimately collapse. Under higher downstream pressure this collapse is relatively violent, which creates high pressure shock waves which cause intermittent intermixing of the components in the fuel stream cavitation zone, resulting in an homogenized fluid with long term stability or lack of separation.
Various factors such as volume, viscosity, upstream pressure, downstream or pump suction pressure, conduit diameter, orifice diameter, fuel temperature and changes in fuel temperature affect the amount of homogenization and the non-separation life of the fuel oil and water mixture. Control of the downstream pressure subsequent to the homogenization orifice has been found to be very important. The downstream pressure or pump suction pressure is directly affected by conditions at the homogenization orifice and by the aperture size in the orifice. Variations in temperature of the intermixing liquids, fluctuations in upstream pressure and erosion of the orifice over time can negatively affect the downstream pressure. For example, a single degree F change in temperature of the fuel can cause a 3 psig change in downstream pressure, and a single psig change in upstream pressure can cause a 0.6 psig change in downstream pressure. These factors can be critical in many systems, since a system with preferred downstream pressure of 30 psig should be maintained within a tolerance of 2 psig plus or minus. To account for these variables and to control the downstream pressure, I have previously developed a system, U.S. Pat. No. 4,493,558, in which the homogenizing orifice is part of a compensating valve whereby the orifice can be adjusted either manually, and where the orifice opening size is automatically adjustable responsive to the downstream pressure. In that patent, a compensating valve for controlling an adjustable orifice is disclosed which incorporates a hydraulic, diaphragm-type valve arranged in fluid communication with the downstream side of the system so as to be directly responsive to any changes in pressure on the downstream side of the orifice. A piston reciprocates the adjustable portion of the compensating valve to decrease the size of the orifice in response to an increase in downstream pressure and to increase the size of the orifice in response to a decrease in downstream pressure.
The present apparatus improves upon that system by providing a high pressure regime subsequent to the pump and a second homogenizing orifice coupled with an automatically responsive compensating valve. This second compensating valve is responsive to pressure in the high pressure regime upstream of the orifice, the valve and orifice acting to further intermix the homogenized fuel oil and water mix as well as to reduce the outlet pressure of the mixture to the desired range for optimum efficiency in the combustion equipment. This two stage cavitation process reduces water droplet size to 4 to 7 microns and breaks up all particles in the fuel oil to less than 10 microns diameter.
It is an object of this invention to provide an apparatus or system which effectively homogenizes a two liquid component stream of fuel oil and water while maintaining proper flow pressure. It is a further object to provide such a system where the homogenization is accomplished using the cavitation process of forcing a high pressure flow of liquid through a relatively small size orifice, where the variation in pressure downstream of the orifice is maintained within relatively precise limits. It is a still further object to provide such a system where the downstream pressure is maintained through the use of a compensating valve operating the adjustable orifice, the compensating valve being directly responsive to the pressure in a particular regime of the flow stream so as to immediately adjust the orifice to either increase or decrease flow and thereby increase or decrease downstream pressure as required. It is a still further object to provide such a system incorporating a pump and two homogenization orifices, one located upstream of the pump suction side and the other located downstream of the pump discharge side, where the pump creates a high pressure regime downstream on the discharge side and the first homogenization orifice is a operated by a first compensating valve responsive to pressure downstream of itself and the second homogenization orifice is operated by a second compensating valve responsive to pressure upstream of itself in the high pressure regime, the second orifice acting to significantly improve homogenization of the fuel oil and water mix.